1. Field of the Invention
The present invention relates to devices for preventing the back flow of water in plumbing systems, and in particular, to vacuum breaker type anti-siphoning mechanisms.
2. Description of Related Art
Plumbing fixtures have been provided which include a hose-connected spray head which can be manipulated by a user to provide a stream of water, for example, to wash hair or to rinse dishes, for example, in a sink.
One problem inherent with such movable spray heads is that the water supply lines can become contaminated if the spray head is immersed in contaminated water (e.g., as is found in a water-filled sink). Should a negative pressure occur in the water supply (e.g., due to a water main break or the use of water at other outlets in the plumbing system) a back flow or siphoning of water from the sink through the spray head and into the plumbing system may occur. This back flow of water contaminates the water supply.
While one or more one-way back pressure check valves are conventionally provided in the plumbing system to prevent the undesirable back flow of water, these check valves do not always prevent the back flow of water due to, for example, the lodging of sediment in the check valves preventing them from closing properly. Accordingly, it is known to provide vacuum breakers in plumbing systems so that when a vacuum condition occurs in the water supply, air is introduced into the plumbing system through the vacuum breaker, preventing waste water from being pulled into the water supply.
U.S. Pat. No. 5,103,856 to Fleischmann discloses an anti-siphoning valve assembly for placement between the outlet tube of a faucet and a spray head. The assembly includes a T-shaped housing having duck-bill check valves in its inlet and outlet passages in order to restrict fluid flow to only one direction through the housing, and a vacuum breaker attached to a sink rim and in fluid communication with a chamber of the T-shaped housing via a flexible conduit. A float is located in the vacuum breaker housing to prevent liquid from exiting the vacuum breaker housing during normal flow conditions and for permitting the plumbing system to be vented when a vacuum condition occurs in the water supply. A problem with this arrangement is that the flexible conduit attached between the T-shaped housing and the vacuum breaker housing forms a dead-end in which water becomes trapped for extended periods of time. Such water can become contaminated (e.g., by bacteria and microbes). The water in the flexible conduit is pulled into the water supply when a vacuum condition occurs in the water supply, thus potentially causing contamination of the water supply. Additionally, the contaminated water in the flexible conduit gradually makes its way into the water supplied to the spray head, which can be undesirable.
U.S. Pat. No. 5,038,814 to Gayton et al. discloses a back flow preventer and vacuum breaker for use with a plumbing fixture, and includes a body having an inlet and an outlet, a chamber connecting the inlet and outlet and an air vent opening into the chamber. A first diaphragm is positioned within the chamber and controls air flow through the vent. A second diaphragm positioned in the chamber controls flow from the inlet into the chamber and includes an integral check valve extending into the outlet.
Page 12 of the Nov. 22, 1988 Minutes of the ANSI/ASME A 112 Committee, Panel 18 schematically illustrates numerous arrangements for locating back flow preventers and vacuum breakers in a plumbing system having hose connected outlets.
Other patents disclosing back flow preventers, with or without vacuum breakers, for hose-connected spray heads include: U.S. Pat. Nos. 4,805,661 and 4,696,322 to Knapp et al.; U.S. Pat. No. 5,079,781 to Gnauert et al.; U.S. Pat. No. 5,095,554 to Gloor; U.S. Pat. No. 4,827,538 to Heimann et al.; U.S. Pat. No. 4,969,483 to Knapp; U.S. Pat. Nos. 4,301,972 and 4,314,673 to Rudelick; U.S. Pat. No. 5,123,437 to Egli et al.; and U.S. Pat. No. 4,508,136 to Kah, Jr.
Additional references disclosing floats used as vacuum breaker check valves include U.S. Pat. No. 3,414,003 to Wyckoff, U.S. Pat. No. 4,821,762 to Breneman, U.S. Pat. No. 926,968 to Stickdorn and a paper presented by Friedrich Grohe at the Mar. 9, 1988 ANSI/AMSE A 112 Committee, Panel 18 meeting, for use with faucets having hose connected outlets.
A back flow preventer device for connection between a supply pipe and a service pipe, and including one-way check valves at an inlet and outlet of a body member, and a spring biased vacuum breaker located in a separate housing attached to the body member by a tube is disclosed in U.S. Pat. No. 4,489,746.
U.S. Pat. No. 3,929,149 to Phillips discloses a back flow preventer for installation in the water discharge line between an automatic dishwasher and a garbage disposer which can be mounted to a sink rim.